Although the function of stress proteins is not entirely clear, it appears that some participate in assembly and structural stabilization of certain cellular and viral proteins, and their presence at high concentrations may have an additional stabilizing effect during exposure to adverse conditions. Neidhardt, F. C. and R. A. Van Bogelen, In: Escherichia coli and Salmonella typhimurium, Cellular and Molecular Biology, (eds. Neidhardt, F. C., Ingraham, J. L., Low, K. B., Magasanik, B. Schaechter, M. and Umbarger, H. E. (Am. Soc. Microbiol., Washington, D.C.), pp. 1334-1345 (1987); Pelham, H. R. B. Cell, 46:959-961 (1986); Takano, T. and T. Kakefuda, Nature, 239:34-37 (1972); Georgopoulos, C. et al., New Biology, 239:38-41 (1972). Phagocytic host cells produce a hostile environment of foreign organisms, and the ability to produce stress proteins has been implicated in the survival of bacterial pathogens within macrophages Christman, M. F. et al., Cell, 41:753-762 (1985).
Mycobacterium (M.) tuberculosis and Mycobacterium (M.) leprae are the etiologic agents of tuberculosis and leprosy, respectively. These diseases afflict 20-30 million people and continue to present a significant global health problem. Joint International Union Against Tuberculosis and World Health Organization Study Group, Tubercle, 63:157-169 (1982); Bloom, B. and T. Godal, Rev. Infect Dis. 5:765-780 (1983). To develop more effective tools for the diagnosis and prevention of these diseases, it is important to understand the immune response to infection by mycobacterial pathogens.
The antibody and T-cell responses to infection or inoculation with killed mycobacteria have been studied in humans and in animals. Human patients with tuberculosis or leprosy produce serum antibodies directed against at least 12 mycobacterial proteins. Some of these proteins are also recognized by well-characterized murine monoclonal antibodies. Mice immunized with mycobacterial lysates produce antibodies that are directed predominantly to six M. tuberculosis and six M. leprae protein antigens. Engers, H. D. Infect. Immun., 48:603-605 (1985); Engers, H. D., Infect. Immun., 51:718-720 (1986). Genes encoding these 12 mycobacterial antigens have been cloned, and recombinant proteins produced from these clones have been used to investigate the human T-lymphocyte response to mycobacterial infection. Husson, R. N. and R. A. Young, Proc. Natl. Acad. Sci., USA, 84:1679-1683 (1987); Young, R. A. et al., Nature, 316:450-452 (1985); Britton, W. J. et al., Lepr. Rev., 57, Suppl. 2, 67-75 (1986).
Protection against mycobacterial disease involves cell-mediated immunity. Joint International Union Against Tuberculosis and World Health Organization Study Group, Tubercle, 63:157-169 (1982); Hahn, H. and S. H. E. Kaufman, Rev. Infect. Dis., 3:1221-1250 (1981). T-lymphocytes cloned from patients or from volunteers immunized with killed mycobacteria have been tested for their ability to recognize the recombinant mycobacterial proteins. Lymphocyte-proliferation assays demonstrate that most of the antigens identified with monoclonal antibodies are involved in the T-cell response to mycobacterial infection or vaccination in mice and in humans. Limiting dilution analysis indicates that 20% of the mycobacterial-reactive CD4+ T-lymphocytes in mice immunized with M. tuberculosis recognize a single protein, the 65-kDa antigen. Kaufman, S. H. E. et al., Eur J. Immunol., 17:351-357 (1987).
The present invention relates to stress proteins and methods of modulating an individual""s (such as a human, other mammal or other vertebrate) immune response. In particular, it relates to the use of such stress proteins in immune therapy or prophylaxis, which results in an induction or enhancement of an individual""s immune response and as an immunotherapeutic agent which results in a decrease of an individual""s response to his or her own cells. In the embodiment in which an individual""s immune response is induced or enhanced, the induced or enhanced response can be a response to antigens, such as those derived from a pathogen or cancer cell, or can be upregulation of the individual""s immune status, such as in an immune compromised individual. In immune prophylaxis, stress proteins are administered to prevent or reduce the effects in an individual of a pathogen, which can be any virus, microorganism, parasite or other organism or substance (e.g., a toxin or toxoid) which causes disease or to prevent or reduce the effects in an individual of cancer cells. In preventing or reducing adverse effects of pathogens which contain stress proteins (e.g., bacteria, parasite, fungus) according to the method of the present invention, an individual""s immune response to the pathogen""s stress protein(s) is induced or enhanced through the administration of a vaccine which includes the pathogen""s stress protein(s) or other stress proteins. The stress protein can be administered alone, as a member or component of a conjugate (e.g., joined to another antigen by chemical or recombinant means such as joined to a fusion partner resulting in a fusion protein), or as an adjuvant or carrier molecule to enhance or obtain a desired immune response to an antigen.
The present invention also relates to compositions which are conjugates comprised of a stress protein joined to another substance or component. For example, the present invention relates to a conjugate in which a stress protein is chemically linked to an antigen, or in which a stress protein is fused to an antigen (e.g., a fusion protein).
The present invention also relates to a method of generating monoclonal or polyclonal antibodies to a substance using a conjugate comprised of a stress protein joined to the substance. In this embodiment, an effective amount of the conjugate (i.e., an amount which results in an immune response in the host) is introduced into a mammalian host which results in production of antibodies to the substance in the host. The antibodies are removed from the host and purified using known techniques (e.g., chromatography).
Preventing or reducing adverse effects of viral pathogens which do or do not contain stress proteins, as well as preventing or reducing the adverse effects of cancer cells according to the present method, is effected by enhancing an individual""s immune surveillance system. Enhancement of immune response can be effected by modulating the immune cells by stimulation with a stress protein (e.g., a bacterial stress protein).
In the embodiment in which an individual""s immune response is decreased, such as is used in treating autoimmune diseases, stress proteins known to be involved in the autoimmune response are administered to turn down an individual""s immune response by tolerizing the individual to the stress proteins. Alternatively, the immune response to stress protein, which is known to occur in autoimmune disease, is reduced by interfering with the ability of immune cells which respond to stress proteins to do so.
A selected stress protein of the present invention can be administered to an individual, according to the method of the present invention, and result in an immune response which provides protection against subsequent infection by a pathogen (e.g., bacteria, other infectious agents which produce stress proteins) or reduction or prevention of adverse effects of cancer cells. Alternatively, a selected stress protein can be administered to an individual, generally over time, to induce immune tolerance against the selected stress protein. For example, a selected stress protein can be administered in multiple doses over time in order to induce immune tolerance against an autoimmune disease such as rheumatoid arthritis.